Q. No.| 1. | The effective focal length is \(15\) cm. |
| 2. | Chromatic aberration is minimized. |
| 3. | Combination behaves like a convergent lens. |
| 4. | All of these. |
| 1. | \(60\) cm | 2. | \(120\) cm |
| 3. | \(30\) cm | 4. | \(180\) cm |
A concave lens of focal length \(25\) cm produces an image \(\frac{1}{10}\text{th}\) the size of the object. The distance of the object from the lens is:
1. \(225\) cm
2. \(250\) cm
3. \(150\) cm
4. \(175\) cm
Choose the correct statement from the following:
| 1. | \(f' = f,f'' =2f\) | 2. | \(f' = 2f, f''=f\) |
| 3. | \(f' =f, f''=f\) | 4. | \(f'=2f, f''=2f\) |
| Column-I | Column-II | ||
| A. |  |
P. | zero |
| B. |  |
Q. | \(P\) |
| C. |  |
R. | \(2P\) |
| D. |  |
S. | \(\dfrac P2\) |
| 1. | A → Q, B → P, C → S, D → R |
| 2. | A → S, B → R, C → Q, D → P |
| 3. | A → Q, B → S, C → Q, D → R |
| 4. | A → S, B → R, C → Q, D → Q |
A lens forms an image of a point object placed at distance \(20\) cm from it. The image is formed just in front of the object at a distance \(4\) cm from the object (and towards the lens). The power of the lens is:
1. \(-2.25\) D
2. \(1.75\) D
3. \(-1.25\) D
4. \(1.4\) D
In the diagram shown below, the image of the point object \(O\) is formed at \(l\) by the convex lens of focal length \(20\) cm, where \(F_1\) and \(F_2\) are foci of the lens. The value of \(x'\) is:
| 1. | \(10\) cm | 2. | \(20\) cm |
| 3. | \(30\) cm | 4. | \(40\) cm |
Two similar plano-convex lenses are combined together in three different ways as shown in the adjoining figure. The ratio of the focal lengths in three cases will be:
1. \(2:2:1\)
2. \(1:1:1\)
3. \(1:2:2\)
4. \(2:1:1\)
A thin equiconvex lens of power \(P\) is cut into three parts \(A,B,\) and \(C\) as shown in the figure. If \(P_1,P_2\) and \(P_3\) are powers of the three parts respectively, then:
| 1. | \(P_1=P_2=P_3\) | 2. | \(P_1>P_2=P_3\) |
| 3. | \(P_1<P_2=P_3\) | 4. | \(P_2=P_3=2P_1\) |
| 1. | \(X+Y\) | 2. | \(\frac{X + Y}{2}\) |
| 3. | \(X-Y\) | 4. | \(\frac{X - Y}{2}\) |
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